This is a competitive renewal of a Multipurpose Arthritis Center that has been in existence since 1977 which supports a multidisciplinary group of clinical, social and basic researchers in a variety of basic and applied projects in rheumatic disease and musculoskeletal disorders. The MAC has been a major force in the development of the Department of Rheumatology/Immunology and, since the last funding period, has taken on added responsibilities in the supervision and support of clinical investigators. Its core units are used extensively by investigators in and outside the Institution. One core, the Morphology Core, will be discontinued as the principal investigator has accepted a new position. A new core in molecular biology is proposed. In the Education, Epidemiology and Health Services Research Component, four projects are proposed. The first examines epidemiology of chronic lyme disease in Massachusetts; the second tests an approach to assist decision making in the critical changes of treatment for patients with rheumatoid arthritis; the third examines a group of individuals with spinal stenosis to assess the outcomes of conservative management versus surgery; the fourth is an examination of the epidemiology of carpal tunnel surgery in Maine and is the first objective evaluation by newer outcome instruments of the conservative and surgical management of carpal tunnel syndrome. Four development and feasibility studies are proposed. One examines the molecular and clinical epidemiology of yersinia reactive arthritis. The second examines genetic predictors of susceptibility and the age of onset of African Americans with SLE; the third uses a mouse model of lyme disease to elucidate mechanisms of disease causation; and the fourth examines gamma delta T cells in rheumatoid arthritis.